It is a 2000 Registration Passat.
I used to be able to stop the noise by pressing the circulation button which has a circular arrow to either recycle the airflow or allow it straight though.
If the main heater motor is removed from the glovebox, it exposes another motor or something like one which has a flap which is moving and causing the noise. It looks like the flow is too weak which causes the flap to move and make a noise. Not sure what the part is maybe the heater or aircon cooling unit maybe?????
It looks like a major job to replace the part as the dashboard has to come out. Does anyone know if it is possible to jam the flap open or closed to stop the noise? How is that best done?
Hoping at 117,000 miles this is not the end of the road for my baby .....